* Scheme ( programming language )

The Scheme language standard requires implementations to recognize and optimize tail recursion.

For example, Scheme has both continuations and hygienic macros, which enables a programmer to design their own control abstractions, such as looping and early exit constructs, without the need to build them into the language.

Conversely, Scheme contains multiple coherent subsets that suffice to construct the rest of the language as library macros, and so the language designers do not even bother to say which portions of the language must be implemented as language constructs, and which must be implemented as parts of a library.

While syntax is commonly specified using a formal grammar, semantic definitions may be written in natural language ( e. g., as in the C language ), or a formal semantics ( e. g., as in Standard ML and Scheme specifications ).

* Scheme ( programming language ), a minimalist, multi-paradigm dialect of Lisp

Scheme is a functional programming language and one of the two main dialects of the programming language Lisp.

Unlike Common Lisp, the other main dialect, Scheme follows a minimalist design philosophy specifying a small standard core with powerful tools for language extension.

A new language standardization process began at the 2003 Scheme workshop, with the goal of producing an R6RS standard in 2006.

In August 2009, the Scheme Steering Committee which oversees the standardization process announced its intention to recommend splitting Scheme into two languages: a large modern programming language for programmers, and a subset of the large version retaining the minimalism praised by educators and casual implementors ; two working groups were created to work on these two new versions of Scheme.

Scheme is primarily a functional programming language.

This section concentrates mainly on innovative features of the language, including those features that distinguish Scheme from other Lisps.

These are the aspects of Scheme that most strongly influence any product of the Scheme language, and they are the aspects that all versions of the Scheme programming language, from 1973 onward, share.

* Atomic strings: A string is no longer an array of characters ( as in Integer BASIC and C ); it is instead a garbage-collected object ( as in Scheme and Java ).

Common Lisp is most frequently compared with, and contrasted to, Scheme — if only because they are the two most popular Lisp dialects.

Common Lisp is sometimes termed a Lisp-2 and Scheme a Lisp-1, referring to CL's use of separate namespaces for functions and variables.

There is a long-standing controversy between CL and Scheme advocates over the tradeoffs involved in multiple namespaces.

In Scheme, it is ( broadly ) necessary to avoid giving variables names which clash with functions ; Scheme functions frequently have arguments named,, or so as not to conflict with the system function.

In CL, any non-NIL value is treated as true by conditionals, such as, whereas in Scheme all non -# f values are treated as true.

These conventions allow some operators in both languages to serve both as predicates ( answering a boolean-valued question ) and as returning a useful value for further computation, but in Scheme the value '() which is equivalent to NIL in Common Lisp evaluates to true in a boolean expression.

GnuCash is written primarily in C, with a small fraction in Scheme.

ICAO is currently opposed to the inclusion of aviation in the European Union Emission Trading Scheme ( EU ETS ).

The Knights of the Lambda Calculus is a semi-fictional organization of expert LISP and Scheme hackers.

Mutual recursion is very common in the functional programming style, and is often used for programs written in LISP, Scheme, ML, and similar languages.

In Python, a distinction between expressions and statements is rigidly enforced, in contrast to languages such as Common Lisp, Scheme, or Ruby.

The Semester Abroad Scheme is a highly competitive programme open to academically outstanding juniors who wish to follow a regular Cambridge degree course as fully matriculated members of the University.

Currently, " Schemer " is commonly used to refer to a Scheme programmer.

There is a portable reference implementation of the proposed implicitly phased libraries for R6RS, called psyntax, which loads and bootstraps itself properly on various older Scheme implementations.

The source code is now specified in Unicode, and a large subset of Unicode characters may now appear in Scheme symbols and identifiers, and there are other minor changes to the lexical rules.

Scheme is a very simple language, much easier to implement than any other language of comparable expressive power.

Hygienic macros have been standardized for Scheme in both the R5RS and R6RS standards.

Both of and have been standardized in the Scheme standards.

The official death toll of workers on the Scheme stands at 121 people.

* The third part of the name refers to primitive functions that are not defined in R5RS ( the official definition of the programming language Scheme ) but are nevertheless important for real world programming like functions allowing to work with regular expressions, with TCP / IP networks, with embedded databases ( e. g. Berkeley DB, GNU database manager ) and a few that provide an interface with the operating system.

Some official documents refer to a Scheme 3245: this is the only numbered tunnel scheme that has never been officially revealed or located by researchers.

Between 1940 and 1945, Sutherland was employed as an official artist in World War II, as part of the War Artists Scheme.

Also in April 2006, the Portable Antiquities Scheme central unit became an official department within the BM, the Department of Portable Antiquities & Treasure.

One benefit of the Job Creation Scheme was that the perception of the restoration changed in official circles.

Once it has been accredited by the UNFCCC a carbon offset project can be used as carbon credit and linked with official emission trading schemes, such as the European Union Emission Trading Scheme or Kyoto Protocol, as Certified Emission Reductions.

He was also a member of the IEEE working group that produced the IEEE Standard for the Scheme Programming Language, IEEE Std 1178-1990.

Lastly, the Scheme standards documents require tail-call optimization, which the CL standard does not.

Currently the newest releases of various Scheme implementations, such as Chez Scheme, Racket, Ikarus, Larceny and Ypsilon, support the R6RS standard.

For instance of the 23 s-expression-based syntactic constructs defined in the R5RS Scheme standard, 11 are classed as derived or library forms, which can be written as macros involving more fundamental forms, principally lambda.

* The latest version of the Scheme standard: R6RS

These include Common Lisp ( ANSI standard document ANSI INCITS 226-1994 ( R2004 )), Scheme ( R5RS and R6RS ), and ISLISP.

While the languages, by themselves, are simple dynamically typed functional cores, the standard distributions of Scheme or Common Lisp permit imperative or object-oriented programming, as well as static typing.

The most current version follows the Scheme R3RS standard.

Many programming languages, including Lisp, Scheme, OCaml, and Haskell have functions for handling association lists in their standard library.

" It called for more random checks and robust enforcement of the scheme and states that " the use of the word ‘ pedigree ’ should be tied to a high standard of breeding ( for health and welfare ) across the board with the KC not just with the few that decide to join the Accredited Breeder Scheme ( ABS ).

However there is no guarantee that if Northern Rock was to fail that the government would top-up any compensation over and above the standard £ 85, 000 offered by the Financial Services Compensation Scheme.

There also exist formulations in Scheme, Perl, Racket, Clojure and Scala, and monads have been an option in the design of a new ML standard.

With languages such as Scheme and Forth, standards may be considered insufficient, inadequate or even illegitimate by implementors, so often they will deviate from the standard, making a new dialect.

Tail call elimination is thus required by the standard definitions of some programming languages, such as Scheme, and languages in the ML family among others.

It is reasonably close to standard Scheme but is not fully R5RS compliant.

The ISO 14001 standard is the most widely used standard for environmental risk management and is closely aligned to the European Eco-Management and Audit Scheme ( EMAS ).

C code can freely create, access, and mutate Scheme objects ; C functions may call Scheme functions and vice versa ; C code may add new types to the Scheme world and take advantage of Guile's garbage collection … Most of the standard Scheme procedures are implemented by C functions, visible to Guile clients ; for example, applications can call the C function, which is the underlying implementation of the Scheme procedures.